<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        //箭头函数
        let sum = function (a,b) {
            return a+b
        }
        //代码只要1行，返回值 不用 return
        let sum2 = (a,b) => a+b

        console.log(sum2(2,3))
    </script>
</head>
<body>

</body>
</html>